Method and device for producing three-dimensional models with a temperature-controllable print head

ABSTRACT

The present invention relates to a method for producing three-dimensional models by a layering technique, particulate build material being applied to a build space, and binder material subsequently being selectively applied to the build material with the aid of a printer, the binder material containing a moderating agent and subsequently being sintered with the aid of a heat lamp, the print head being protected against overheating by active and/or passive cooling.

FIELD OF THE INVENTION

The invention relates to a method and a device for producingthree-dimensional models according to the definition of the species inPatent Claim 1.

BACKGROUND OF THE INVENTION

A method for producing three-dimensional objects from computer data isdescribed in the European patent specification EP 0 431 924 B1. In thismethod, a particulate material is deposited in a thin layer onto aplatform, and a binder material is selectively printed on theparticulate material, using a print head. The particle area onto whichthe binder is printed sticks together and solidifies under the influenceof the binder and, if necessary, an additional hardener. The platform isthen lowered by a distance of one layer thickness into a build cylinderand provided with a new layer of particulate material, which is alsoprinted as described above. These steps are repeated until a certain,desired height of the object is achieved. A three-dimensional object isthereby produced from the printed and solidified areas.

After it is completed, this object produced from solidified particulatematerial is embedded in loose particulate material and is subsequentlyremoved therefrom. This is done, for example, using an extractor. Thisleaves the desired objects, from which the remaining power is removed,for example by brushing.

Other powder-supported rapid prototyping processes work in a similarmanner, for example selective laser sintering or electron beamsintering, in which a loose particulate material is also deposited inlayers and selectively solidified with the aid of a controlled physicalradiation source.

All these methods are referred to collectively below as“three-dimensional printing methods” or 3D printing methods.

Of all the layering techniques, 3D printing based on powdered materialsand the supply of liquid binder is the fastest method.

Different particulate materials, including polymer materials, may beprocessed using these methods. However, the disadvantage here is thatthe particulate material feedstock may not exceed a certain powderdensity, which is usually 60% of the density of the solid.

Nevertheless, the strength of the desired components depends to asignificant extent on the density reached. For a high strength of thecomponents, it would therefore be necessary to add 40% and more of theparticulate material volume in the form of the liquid binder. This is arelatively time-consuming process, not only due to the single-dropsupply, but also due to many process problems which arise, for example,from the inevitable reduction of the amount of liquid duringsolidification.

In another embodiment, which is known to those skilled in the art as“high-speed sintering,” abbreviated as HSS, the particulate material issolidified by supplying infrared radiation. The particulate material isphysically bound using a melting operation. The comparatively poorabsorption of thermal radiation in colorless plastics is utilized here.However, this absorption may be increased many times by introducing anIR acceptor, also known as a moderating agent, into the plastic. The IRradiation may be introduced in different ways, e.g., using a rod-shapedIR lamp, which is moved evenly over the build space. The selectivity isachieved by printing the particular layer with an IR acceptor in atargeted manner. The IR radiation is coupled into the particle materialin the areas that are printed much more effectively than into theunprinted areas. This results in a selective heating in the layer beyondthe melting point and thus to selective solidification. This process isdescribed, for example, in EP1740367B1 and EP1648686B1. In thesepublications, a simple device is also demonstrated, which, however, isoperational only on a small scale and is not suitable for printinglarger build spaces, since it lacks a corresponding temperaturemanagement system.

The object of the present invention is thus to provide a scalabledevice, with the aid of which the HSS process is facilitated or which atleast improves the disadvantages of the prior art.

The device according to the invention comprises a build plane, ontowhich the layers of the particulate material are deposited. The buildplane is moved layer by layer through a build space, using a linearpositioning unit. The build space may be defined, for example, by a jobbox, which may be removed from the device at the end of the process. Thedevice parts for applying the layers move within a process chamber. Thedevice for applying the layer may be, for example, a vibration coater(DE10216013B4) or a counter-driven roller (EP0538244B1) or a simplescraper, which applies the particulate material to the build space in athin layer that is 20 μm to 300 μm thick, preferably 50 μm to 200 μmthick.

A print head, which has at least one nozzle and prints the particularlayer with an IR acceptor, is also situated in the process chamber.

In principle, it is possible to deposit the IR acceptor in a vector-likemanner onto the build space in the form of a jet or in the form ofsingle drops. To achieve a suitable resolution, the jet or drop sizeshould be in a range from 20 to 200 μm. To achieve higher processspeeds, it is advantageous to use a print head which generates singledrops with the aid of a large number of nozzles and moves over the buildplane in a grid-like pattern. An IR lamp, which illuminates the buildplane as a whole or parts of the build plane in the form of a spot or aline, is also situated in the process chamber. In the latter two cases,the IR lamp must be moved over the build space with the aid of apositioning unit in order to illuminate the entire build space. Arod-shaped IR lamp has proven to be advantageous, which extends over theentire width of the build space and lights up a relatively narrow areain the positioning direction. The positioning units for moving thecoater, the print head and the IR lamp may be designed independently ofeach other or in combination. The lamp embodied in the shape of a rod isadvantageously situated on the back side of the coater unit. In thismanner, the coater may carry out the exposure to light when returning tothe starting position, while the movement in the other direction is usedfor coating, possibly with reduced lamp power. The print head in thisembodiment may be mounted on another moving axis farther behind [sic;the] lamp.

The build plane preferably moves in a build cylinder which is open atleast on the side of the build plane and forms the build space togethertherewith. The build space may advantageously be removed from the deviceat the end of the printing process. The device may then carry out a newlayering process by inserting another build space.

The HSS process may be used to process many polymer materials inparticulate form, for example polyamide. Graphite, for example, may beused as the IR acceptor, which is mixed in a carrier fluid in the formof a suspension. Various easy-to-print fluids, such as isopropylalcohol, dimethyl succinate and, with restrictions, ethyl alcohol orwater, are suitable as carrier fluids.

The process must be set in such a way that the temperature in theprinted areas is above the melting point of the particulate material, atleast for a short period of time. In the case of polyamide 12, or PA 12for short, this temperature is approximately 180° C. On the other hand,the temperature in the unprinted areas should be as low as possible,since the polymer material may change irreversibly even at lowertemperatures.

The quantity of IR energy introduced into the particulate material maybe set, for example, by means of the lamp power or by means of the speedat which the rod-shaped lamp moves over the build space. Thedisadvantage of the method is that the carrier fluid for the IR acceptorevaporates in the printed areas and, during this process, thetemperature thereby decreases in the areas. It is therefore advantageousto increase the temperature in the build space to a higher level withthe aid of suitable measures in order to minimize the necessarytemperature difference that must be overcome with the aid of the lamp.Care should also be taken to avoid selecting too high a temperature inorder to minimize damage to the particulate material. In principle, itis also possible to preheat the particulate material prior to coating.However, it has been demonstrated that the particulate material veryquickly adapts to the ambient temperature during and after coating anddissipates the thermal energy again. A temperature range of 60° C.-120°C. for PA 12 has been demonstrated to be advantageous for a build spaceatmosphere. A temperature range of 75° C. to 95° C. is even moreadvantageous. It is possible that the particulate material would alreadybegin to react with the oxygen in the air at these temperatures. It maytherefore be necessary to apply a protective gas to the build space.Nitrogen, for example, is suitable as the protective gas; other gasessuch as argon may also be used.

To increase the temperature in the build space to the desired level, itmay be necessary to provide additional heating means in the device. Thismay be done, for example, in the form of IR radiators above the buildspace, which heat the entire build space as evenly as possible. However,it would also be conceivable to remove the air from the process chamber,heat it using corresponding means, such as a heater battery, and blow itback into the process chamber in a targeted manner. Moreover, it isadvantageous if the heat in the process chamber is maintained at apreferably constant level. For this purpose, a temperature controller isadvantageous, which regulates the heating means in the build space ininteraction with a temperature sensor. The temperature gradient on thebuild space should not exceed 10° C. To simplify the temperatureregulation, it is desirable if as little heat as possible is lost to thesurroundings. It is therefore necessary to insulate the process chamberusing suitable measures and to provide corresponding seals on doors andflaps. The same applies to the build space, which is also designed insuch a way that little heat is dissipated to the surroundings. This isdone by providing the build cylinder with a double-walled design,including corresponding insulation at the contact points. In principle,it is also possible to compensate for the temperature loss in the buildspace by means of an active heating, e.g., of the inner walls of thebuild cylinder and/or the building platform. Another option is toactively introduce preheated gas into the build space, which acts as anenergy carrier and transfers the heat to the particulate materialfeedstock. The gas may be introduced, for example, by means of bores inthe building platform.

So-called filament dispensers, which deflect a fluid stream onto thebuild space via a nozzle, may be used as the print head. The fluidstream contains the IR acceptor, e.g., in the form of solid graphiteparticles in a solvent suspension. The nozzle should have a diameter of0.1-0.5 mm for a suitable print resolution. A valve may be insertedupstream from the nozzle, which is able to quickly switch the fluidstream. The nozzle should be moved over the build space at a shortdistance of only a few mm to ensure the positioning accuracy of thedeposition of the fluid stream. The filament dispenser is moved over thebuild space in a vector-like manner with the aid of at least two linearaxes. The kinematics preferably comprise a portal with three linearaxes. In principle, other kinematics of motion are also conceivable, forexample, an articulated arm robot, which guides the filament dispenserover the build space.

In one preferred embodiment, the IR acceptor is dispensed in fluid formonto the build space using a print head which includes a large number ofsingle-drop generators. Print heads of this type are known from manyapplications, including 3D printing, where a binder instead of the IRacceptor is dispensed in layers onto a particulate material.

Drop generators of this type work according to different principles, forexample the piezo principle or the bubblejet principle. In addition tothese so-called drop-on-demand single drop generators, continuoussystems are also known, in which a switchable stream of single drops isgenerated. In principle, all these systems are suitable for theaforementioned task; however, the piezo systems have significantadvantages with regard to lifespan, performance and economicfeasibility.

Piezoelectric printing systems work with one or multiple open nozzles.The nozzle diameters are usually less than 80 μm. A pressure pulse isbriefly applied to the fluid in equally small pump chambers with the aidof a piezoelectric actuator. The fluid is significantly accelerated inthe nozzles and emerges therefrom in the form of drops. Due to thisfunctionality, certain limits are imposed on the present device. Thus,the fluid must have a relatively low viscosity. The viscosity shouldpreferably be less than 20 mPas. In addition, the IR acceptor particlesmixed into the carrier fluid must be much smaller than the narrowestchannel width in the printing system. As a result, the particles arepreferably smaller than 5 μm and even more preferably smaller than 1 μm.Due to the operating principle of the printing system using the pressuresurge, it is necessary for all channels and the pump chambers to befilled with the fluid without any gas bubbles. To maintain thiscondition during operation as well, it is necessary either to select acarrier fluid which has an evaporation temperature above the operatingtemperature or to control the temperature of the fluid in such a waythat no phase transition of the fluid takes place. Moreover, thepiezoelectric actuators have a limit temperature up to which theyusually may be heated without sustaining irreversible damage. Thistemperature is usually under 120° C.

It is apparent from the above discussion that the printing system mustbe protected against excessive IR radiation in the process chamber, onthe one hand, and the temperature of the printing system must beregulated independently with respect to the process chamber temperature,on the other hand.

The printing system may be protected against the IR radiation by meansof corresponding shielding and/or by the distance to the radiationsources. This may be effectively accomplished with radiation sourcesfrom above and from the sides. However, it is difficult to protect theprint head against radiation from below, since it must move at a veryshort distance of 1-5 mm, preferably 2-3 mm from the powder bed. Thisshort distance is necessary to ensure a precise positioning of the smallfluid droplets on the build space. For this reason, it is necessary tokeep the dwell time of the print head over the hot build space as shortas possible.

Despite the aforementioned measures, the desired temperature of theprinting system, which is 40° C.-60° C., is much lower than thetemperature of the process chamber. Corresponding cooling measures mustbe provided therefor.

These measures are divided into internal cooling, external cooling andpartitioning. Only a combination of different measures facilitates aprecise regulation. Regulating the temperature is necessary, since theviscosity of the print fluid is greatly dependent on the temperature.The dispensing capacity of the print head, in turn, is linked to theviscosity. Consequently, an imprecise regulation may result influctuating supply of the moderating agent.

This may result in component distortion. For the purpose of moredetailed explanation, the invention is described in greater detail belowon the basis of preferred exemplary embodiments with reference to thedrawing.

In the drawing:

FIG. 1 shows a method known from the prior art.

FIG. 2 shows a diagram of the process sequence of a 3D printer whichoperates according to the HSS principle;

FIG. 3 shows a graphic representation of the dwell times of the printhead above the heated build space in a process according to FIG. 2;

FIG. 4 shows a representation of the structure of the print headaccording to the prior art;

FIG. 5 shows a diagram of the control of the temperature of a print headaccording to the prior art;

FIG. 6 shows an expanded diagram of the control of the temperature of aprint head according to the prior art, including internal or externalprint head cooling;

FIG. 7 shows a diagram of the cooling process by means of flushing ornozzle actuation;

FIG. 8 shows an isometric view and a side view of a print module, withan indication of the flow lines of the cooling air;

FIG. 9 shows a sectional view of the coolant channels for cooling themodules and the cover plate;

FIG. 10 shows a sectional view of the Peltier elements for activelycooling the print head with the aid of massive cooling lines;

FIG. 11 shows a sectional view of a print head, including surfaces forcooling through evaporation;

FIG. 12 shows a top view of a preferred device having partitioning in ablock diagram;

FIG. 13 shows a side view of one preferred embodiment, including apartition wall;

FIG. 14 shows a top view of one preferred embodiment, includingdifferent partitioning means;

FIG. 15 shows a side view of one preferred embodiment, including an aircurtain;

FIG. 16 shows a side view of one preferred embodiment, including a printhead air cooling means;

FIG. 17 shows a side view of a device for active contacting with afluid-cooled cleaning device and a cooling block;

FIG. 18 shows a top view of a device according to the invention,including cooled build space edges;

FIG. 19 shows a top view of one preferred embodiment, including a linearlamp, segmented activation and a diagram for the movement speed.

FIG. 1 shows a known device according to the prior art. It is used toproduce bodies such as object 103. Body 103 may have a nearly arbitrarycomplexity. The device is referred to below as a 3D printer.

The process of constructing a body 103 begins in that movable buildingplatform 102 is moved to its highest position in device 104. At leastone layer thickness is also present between building platform 102 andthe lower edge of coater 101. The coater is moved to a position in frontof build space 111 with the aid of an axis system, which is notillustrated. In this position, coater 101, including its stock 113 ofparticulate material, is caused to vibrate. The particulate materialflows out of gap 112. Outflowing material 110 fills the still emptylayer due to a forward movement 106 of coater 101.

Subsequently or even during the movement of coater 101, print head 100is set in motion by an axis system, which is also not illustrated. Thelatter follows a meandering path 105, which passes over the build space.According to the sectional diagrams of body 103 to be produced, theprint head dispenses drops of binder 109 and solidifies these areas.This basic principle remains the same regardless of print head 100 used.Depending on the size, in extreme cases, meandering path 105 is reducedto a simple forward and backward movement.

After printing, building platform 102 is moved in direction 108. A newlayer 107 for coater 101 is generated thereby. The layer cycle beginsall over again when coater 101 returns to its starting position.Repeatedly carrying out this cycle produces component [sic; body] 103 inthe end. After the building process, component [sic; body] 103 may beremoved from the loose powder still surrounding it.

The solidification process described above, in which the particles ofthe particulate material are sintered, is one variant of this process.FIG. 2 shows the sequence of a method of this type. It is an expansionof the 3D printer described above.

The representation under I shows the printing process, which takes placein a manner similar to the above description. Print head 100 undergoes ameandering movement and deposits drops, including moderating agent 109,in the area of component [sic; body] 103. In terms of many of its parts,device 104 is structured like a 3D printer. The drop generation ispreferably based on the piezoelectric principle, since print headshaving maximum lifespans may be built hereby. This effect may be usedonly up to a certain limit temperature TLimit. Above this temperature,the drop generation is disturbed, or the drop generator sustainsirreversible damage.

Step II deviates from the above description. A heat lamp, whichgenerates radiation 201 adapted to the moderating agent, is guided overthe build space. When it reaches the printed sites, the heat iseffectively coupled into the particulate material and causes it to besintered. The rest of the build space also absorbs not inconsiderableamounts of heat.

Process steps III and IV are again entirely similar to the descriptionof 3D printing. Building platform 102 is first lowered into device 104in direction 108. Coater 101 then fills layer 110 with new particulatematerial.

FIG. 3 shows a top view of a preferred device according to theinvention. Print head 100 is omitted for the purpose of betterillustrating meandering print head path 105. It is apparent that theprint head executes large sections of its movement over build space 111.Simplified, the build space has a fixed temperature T111. At thebeginning of the process, the print head has temperature T100=TBegin.FIG. 3 also shows a schematic representation of the dwell time of printhead 100 over build space 111. The diagram shows the process steps fromFIG. 2.

Assuming that the build space has temperature T111, the followingconditions arise, which are illustrated in the other diagrams in FIG. 3.The print head heats up over the build space. Afterwards, it may againtransfer heat to the surroundings in its idle position. Depending on theheat absorption over the build space and the heat dissipation in theidle position, a stationary temperature between start temperature TStartand build space temperature T111 sets in. It is demonstrated that, if ahigher printing capacity is desired, the print head must be protectedagainst overheating above TLimit with the aid of active and/or passivecooling. To ensure uniform dispensing capacities, the print head mustalso be maintained within a very narrow temperature range. Temperaturesof 40-60° C. are particularly preferred in this case. According toexperience, a control of +−2° C. delivers good print results.

FIG. 4 shows the structure of a print head 100 according to the priorart. Various assemblies are integrated into housing 212. Print modules400 are essential for drop generation 109. These print modules containthe nozzles, the piezoelectric drives and the fluid system fordistributing the fluid. A heater is usually also integrated fortemperature regulation. These modules 400 are frequently purchased fromprint head manufacturers such as Dimatix, Xaar, Seico, Epson, Konica orKyocera. Intervention into the inner structure is not possible. Modules400 are connected to a storage tank 401, which contains print fluid 408,by hoses, a valve 406 and a filter 407. Electrical connections exist toheating controller 413 and data electronics 414. The connections are runto the outside (415, 416). The storage tank is connected tounderpressure, overpressure and the refill line by additional linesswitched by valves (409, 410 and 411). These lines are again run to theoutside (417, 418 and 419).

On the underside, the print head is protected against the penetration offluids or contaminants by a cover plate 402. The modules and the coverplate absorb heat 404 in the form of radiation and convection during thetravel over build space 111. If the temperature exceeds the setpoint ofthe heating controller, the temperature may no longer be held at aconstant level.

FIG. 5 shows the heating controller of existing print heads as a blockdiagram. Heating system 501 itself is controlled by a power controller503. It receives its control signals from a controller 504, which,together with a sensor 500, detects the temperature directly in module400 and thus implements a closed control circuit. The heat losses due toheat conduction to the surrounding parts, the convection in the housingand the thermal radiation losses are identified by 502. Energy is alsotransferred along with heated fluid drops 109 if the temperature of thedrops is higher than the temperature of the refilled fluid. All lossesmust be compensated for by the heating system. The temperature at thelower end of the module is relevant for drop formation.

FIG. 6 shows the design of a print head according to the invention. Amassive heat flow 404 is added to the aforementioned variables in thiscase. In the HSS process described above, this heat flow is greater thanthe dissipated amounts of heat. The control by the print head-internalheating system may be facilitated only by introducing additional cooling600. Cooling system 600 may include all preferred embodiments accordingto the invention.

The form of heat dissipation illustrated in FIG. 7 is also covered by600. In principle, two options exist. On the one hand, cold print fluidmay be pressed through the print head. For this purpose, an overpressure700 is applied to module 400 or to storage tank 401 (FIG. 4). A largeamount of fluid is dispensed, and colder fluid enters module 400. In onepreferred embodiment of the invention, the fluid enters print head 100or print module 400 from a reservoir outside the build space at roomtemperature via insulated lines. This form of cooling may likewise takeplace via the drop generator of the print head. As in standardoperation, an overpressure 702 is present at the tank.

The intensity of this form of cooling must be ascertained by controller504 of print head heating system 501. If the temperature leaves thecontrol range in the upward direction, more intensive cooling isrequired. This scenario may be detected by the switching times ofheating system 501.

The cooling of module 400 may also be achieved via its housing. For thispurpose, compressed air 800 may flow to the housing to compensate forheat absorption 404 from below. The compressed air nozzles may also bedisposed in such a way that the flow rises vertically on the printmodule. In both embodiments of the invention, cover plate 402 (FIG. 4)must seal the modules toward the build space so that no particulatematerial is swirled up.

FIG. 9 shows another preferred embodiment of the invention. In thiscase, heat 404 to be dissipated is transferred from module 400 to afluid by heat conduction. For this purpose, contact blocks 900 on module400 and cover plate 402 are disposed in a way that facilitates good heattransfer. Contact blocks 900 have bores 903, in which cooling fluid 901may flow. Connections 902 connect the contact blocks to a hose system,which passes out of the print head and the warm build space. The hosesystem has an insulated design. Depending on the accumulating heat,cooling fluid 901 is then cooled passively or actively.

FIG. 10 shows a likewise preferred device. In this case, excess heat 404at module 400 is also dissipated via contact blocks 1000. In this case,the latter are in contact with Peltier elements 1002 via massive copperconnections 1001. The Peltier elements pump the heat out of print headhousing 412 when a voltage is applied to contacts 1004.

The evaporation of a liquid may also be used for cooling. FIG. 11 showsan arrangement of this type. Heat 404 at module 400 is dissipated tocover plate 402 by heat conduction. A fluid 1102, which has a suitableevaporation point, is continuously redispensed thereto. The energy istaken from steam 1100 and guided out of the print head using a dischargesystem 1101 to avoid harmful condensation. For example, if water isselected as the fluid, temperatures around 100° C. may be controlled.

FIG. 12 shows one preferred embodiment in the form of a block diagram.Print head 100 is separated from the build space by a partition 1200. Inthe phase of sintering, lowering and coating (FIG. 3, II, III, IV),print head 100 may thus cool without absorbing any more radiation frombuild space 111. The convection is also reduced. In the same manner,another partition 1201 may ensure that no additional heat reaches printhead 100 due to the still warm lamp 200 during the passage of print head105.

FIG. 13 shows a side view of one preferred embodiment of the invention.Partition 1300 for print head 100 is rotatably supported. Print head 100may thus strike the partition and reach build space 111. An energyexchange takes place only when it passes through. Partition 1300 forms achamber for the print head in which it may cool. Likewise, partition1301 may be designed for coater 101 and lamp 200.

The partitions illustrated in FIG. 13 may also be designed to be active,as shown in FIG. 14. Once again, one partition 1400 may be provided forprint head 100, and one partition 1401 may be provided for coater 101and lamp 200. Compared to the rotatably supported partition, this hasthe advantage of lesser restrictions in the movement of the units inbuild space 111. The opening times may also be designed to be veryshort. For example, pneumatic actuators or electrically driven spindlesare suitable as drives.

FIG. 15 shows one preferred embodiment of the partitioning means. Movingparts are dispensed with. Nozzles 1501, 1500, 1502 allow air havingdifferent temperatures to flow in the direction of build space 111 as acurtain. If a laminar flow is set, only a limited mixing of the airmasses 1503, 1505 and 1504 takes place. The temperature may becontrolled and also regulated in segments via corresponding heating andcooling units.

According to the invention, it is not only possible to cool print head100 by partitioning or from the inside, but the print head may also becooled from the outside. FIG. 16 shows a design of this type. Print head100 is flushed with cooling air 1601 and 1603. This air is dischargedfrom nozzles 1600 and 1602. The flow of cooling air should not interactwith the particulate material. It is therefore particularly preferred tocombine the cooling with a partitioning.

FIG. 17 shows another means of cooling the print head from the outside.Print head 100 is brought directly into contact with a heat-dissipatingmaterial. This may be a fluid which absorbs the heat. This may becombined with a cleaning device for the print head. A counter-rotatingroller 1700 may be brought into contact with print head 100 moving indirection 105. The roller, which has been moistened by a shower 1702 ora fluid-filled basin 1703, absorbs heat from the print head. A goodthermally conductive body 1701 may also be pressed onto cover plate 102of print head 100. This body, in turn, is passively or actively cooled,for example using a cooling fluid 1704.

Print head 100 may cool not only in its idle position but also on itspath 105 on the edge of build space 111. For this purpose, build spaceedges 1800 must be colder than the build space. This may be achieved bythe fact that edges 1800 of build space 111 are designed as pipesthrough which cooling air 1801 flows.

FIGS. 19 and 20 show one particularly preferred embodiment of theinvention. FIG. 19 shows the design of lamp 200 in an essentially linearembodiment. A homogeneous illumination of build space 111 is achieved.Due to the control, the direct influence of the print head may beminimized. Since cooler areas may occur on the edge of the build space,despite a uniform radiation power, due to the air circulation,additional segments 2000 may be mounted here, or a lamp with segmentedcontrol of the power may be used.

FIG. 19 also shows a diagram for a particularly preferred control of thelamp movement of a linearly designed lamp. Due to the convection onbuild space 111, it is sensible to irradiate the edges at a slowermovement speed while maintaining a constant power. It is likewisepossible to adjust the power. The inertia of the lamp imposes limits onthe method.

LIST OF REFERENCE NUMERALS

-   100 Print head-   101 Coater-   102 Building platform-   103 Body-   104 Device-   105 Print head path-   106 Coater path-   107 Built layers-   108 Direction of building platform-   109 Microdrops-   110 Particulate material roll-   111 Build space-   112 Coater gap-   113 Powder stock-   200 Heat lamp-   400 Print module-   401 Storage tank-   402 Cover plate-   403 Heated surface-   404 Heat transfer-   406 Valve-   407 Filter-   408 Printing fluid-   409 Valve for underpressure-   410 Valve for overpressure-   411 Valve for refilling-   412 Print head housing-   413 Heating controller-   414 Data electronics-   415 Feed-through for data electronics-   416 Feed-through for heating controller-   417 Feed-through for underpressure line-   418 Feed-through for overpressure line-   419 Feed-through for refilling line-   500 Temperature sensor-   501 Heating-   502 Heat dissipation-   503 Power controller-   504 Controller-   600 Cooling-   700 Overpressure-   701 Overpressure jet-   702 Underpressure-   800 Flow, horizontal-   801 Flow, vertical-   802 Air nozzles-   900 Contact block-   901 Cooling fluid-   902 Cooling line*-   903 Cooling pipe-   1000 Contact block-   1001 Massive heat conductors-   1002 Peltier element-   1003 Pumped-off heat-   1004 Electrical contacting-   1100 Steam-   1102 Fluid-   1101 Steam guidance-   1200 Print head partition-   1201 Coater partition-   1300 Rotatable print head partition-   1301 Rotatable coater partition-   1400 Movable print head partition-   1401 Movable coater partition-   1500 Air nozzles for build space flow-   1501 Air nozzle for print head flow-   1502 Air nozzle for coater flow-   1503 Print head flow-   1504 Coater flow-   1505 Build space flow-   1800 Build space edge-   1801 Cooling air for build space edge-   2000 Additional lamps

1-17. (canceled)
 18. A method for building a three-dimensional model bya layering technique comprising: applying a layer of particulateconstruction material onto a construction field, subsequentlyselectively applying a moderating agent onto the construction materialwith an ink-jet print head for preparing a printed area, supplyinginfrared radiation energy for melting the particulate material in theprinted area, and protecting the print head from excessive heating byactive and/or passive cooling; wherein the layering technique employs adevice having a temperature control system which, in interaction with atemperature sensor, controls the heating possibilities in a constructionspace atmosphere to 60° C. to 120° C., wherein a temperature gradient onthe construction field does not exceed 10° C. 19-20. (canceled)
 21. Themethod of claim 18, wherein the print head has a temperature sensor, atemperature control and internal means for cooling and heating.
 22. Themethod of claim 18, wherein the device includes a cooling component forcooling a temperature of the print head lower than the temperature ofthe construction space atmosphere, wherein the cooling of the print headtakes place with the aid of the print medium to be printed; or thecooling of the print head takes place with the aid of cooling air whichis flushed around sensitive parts in the interior of the print head; orthe cooling of the print head takes place by dissipating heat with theaid of an additional fluid medium; or the cooling of the print headtakes place with the aid of Peltier elements.
 23. The method of claim22, wherein the cooling of the print head takes place with the aid ofthe print medium to be printed.
 24. The method of claim 22, wherein thecooling of the print head takes place with the aid of cooling air whichis flushed around sensitive parts in the interior of the print head. 25.The method of claim 22, wherein the cooling of the print head takesplace by dissipating heat with the aid of an additional fluid medium.26. The method of claim 22, wherein the cooling of the print head takesplace with the aid of Peltier elements.
 27. The method of claim 22,wherein an evaporator is arranged in the print heat for cooling.
 28. Themethod of claim 18, wherein the method includes sensing a temperature ofthe print head.
 29. The method of claim 18, wherein the print head has apartition protecting it from residual energy of the construction spaceand of the particulate material, and from the active energy supply onthe construction field.
 30. The method of claim 29, wherein the petitionis a sliding wall.
 31. The method of claim 18, wherein the print head ismovable behind a flexible or fixed wall in the construction space. 32.The method of claim 31, wherein sensors are mounted in the wall.
 33. Themethod of claim 18, wherein the print head includes external heating.34. The method of claim 18, wherein the device independently regulates atemperature of the print head relative to a temperature of theconstruction space atmosphere.
 35. The method of claim 18, wherein alamp is used to supply the energy which essentially evenly covers theentire construction field.
 36. The method of claim 18, wherein avariation in the temperature of the print head is controlled to +/−2° C.37. A method for building a three-dimensional model by a layeringtechnique comprising: applying a layer of particulate constructionmaterial onto a construction field, subsequently selectively applying amoderating agent onto the construction material with an ink-jet printhead for preparing a printed area, supplying infrared radiation energyfor melting the particulate material in the printed area, and protectingthe print head from excessive heating by active and/or passive cooling;wherein the layering technique employs a device having a temperaturecontrol system which, in interaction with a temperature sensor, controlsthe heating possibilities in a construction space atmosphere to atemperature of 60° C. to 120° C., and the device independently regulatesa temperature of the print head relative to the temperature of theconstruction space atmosphere.
 38. The method of claim 37, wherein thedevice actively cools the print head.
 39. The method of claim 38,wherein a variation in the temperature of the print head is controlledto +/−2° C.